The Informatics Handbook: A guide to multimedia communications and broadcasting

751 Pages·1996·42.117 MB·English

by  Stewart Fist (auth.)

The Informatics Handbook
Telecommunications Technology and Applications Series
Series editor: S. Sharrock
Titles available
1. Coherent Lightwave Communications Technology
Edited by Sadakuni Shimada
2. Network Management
Concepts and tools
Edited by ARPEGE Group
3. The Informatics Handbook
A guide to multimedia communications and broadcasting
Stewart Fist
The Informatic s Handbook
A guide to multimedia
communications and broadcasting
by
Stewart Fist
Freelance technical writer and journalist, Australia
E3
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
First edition 1996
© 1996 Stewart Fist
Originally published by Chapman & Hall in 1996
ISBN 978-0-412-72530-2 ISBN 978-1-4615-2093-1 (eBook)
DOI 10.1007/978-1-4615-2093-1
Apart from any fair dealing for the purposes of research or private study, or
criticism or review, as permitted under the UK Copyright Designs and Patents
Act, 1988, this publication may not be reproduced, stored, or transmitted, in any
form or by any means, without the prior permission in writing of the publishers,
or in the case of reprographic reproduction only in accordance with the terms of
the licences issued by the Copyright Licensing Agency in the UK, or in
accordance with the terms of licences issued by the appropriate Reproduction
Rights Organization outside the UK. Enquiries concerning reproduction outside
the terms stated here should be sent to the publishers at the London address
printed on this page.
The publisher makes no representation, express or implied, with regard to the
accuracy of the information contained in this book and cannot accept any legal
responsibility or liability for any errors or omissions that may be made.
A Catalogue record for this book is available from the British Library
^Printed on permanent acid-free text paper, manufactured in accordance with
ANSI/NISO Z39.48-1992and ANSI/NISO Z39.48-1984 (Permanence of Paper)
Acknowledgements
To Jillian Fist
Simply to thank my wife and partner Jillian for her help and patience during the
production of this book, would be to understate her involvement. For the last year we
have both been working most of each week upgrading our paper and electronic
databases, checking information, subbing copy, keying in the corrections, and
formatting the Camera Ready Copy. For Jillian, this has been full-time involvement;
this book is as much the product of her work, as it is of mine.
I couldn't (and wouldn't) have done this alone: the project would have been
abandoned half-way without her constant help and support. S.F.
I
am a independent writer, so the editors I work with in Australia have also made valuable contributions. They have both
supported me over the years this book has been a 'work-in-progress', and encouraged me to publish what was Originally just
an enormous jumble of personal reference files.
Mark Smeaton of Australian Communications magazine has been particularly encouraging over the many years we've
worked together, and also Chris Moriatt)' of LAN Magazine and Jeremy Horey of The Australian newspaper. Stuart Sturrock
of Mobile Communications International in the UK took an early draft to Chapman & Hall and convinced technical editor
Daniel Brown the project was worth pursuing. They are obviously both men of insight and intelligence!
And then there's the production staff at Chapman & Hall; particularly Alexandra Stibbe and Penny Sucharov who have
laboured over the style, the cross-referencing, and the problems I have with American spelling. To the uninitiated, trying to
correct this stuff must have been about as alien a task as subbingJapanese Kanji. I thank them all for their efforts and tolerance.
Lastly, there's the electronic forums on CompuServe and the Internet. There's no better place to ask questions and get
answers than here. And just by reading telecommunications and multimedia forums, digest and Usenet material regularly, you
soon get a taste for the different ways terms are being used within these rapidly developing international electronic
communities. I always received polite answers to what must have often been rather stupid questions. Patrick Townson
(Telecom Digest) and Scott Loftesness (Telecommunications Forum) are the two sysops who most obviously come to mind
here. They run useful and lively discussion groups.
Lastly, I must thank the thousands'of marketing people whose job it is to confuse all discussion in this area by inventing
new and more exotic terms and acronyms. Without them, this book would have only been half the size.
Technical History
ThiS book began life as a series of notes on an Apple II. My background is in television current affairs and film production,
and I came into the computing and communications industries late in life. I found then, as I find now, that the terminology
used in these industries is often totally confusing and contradictory, and this was a way of tracking and understanding.
The serious development of the database only really became possible when Bill Atkinson wrote that marvellous
program, HyperCard, and I mounted it on my Macintosh. I still don't know whether to call it a database or system software,
but whatever it is, HyperCard is the best possible way for an information magpie like me to store information. And, as I later
found, HyperCard is also the best way to create intelligent sorting algorithms (sorry, 'handlers') and complex file-extraction
programs, when the time came to create camera-ready copy.
The output of the HyperCard files were passed through to FrameMaker 3.0 which is probably the best book publishing
program ever written. It creates the many styles and formats, and automatically tracks page references, and creates the
running heads at the top of each page. The typeface is Garamond Narrow, which was forced on us by the sheer volume of words
(the original files have over a million, and this book has 650 000 words). Without a condensed typeface, the book would have had
many more pages and been much more expensive. The CRC output was from a Hewlett Packard LaserJet IIP printer, directly onto
A4 copy paper, using 12 point type. This was photo-reduced (linear 80%, which is a 1.6-times resolution improvement) in the plate
making process to the Crown Quarto book size.
Introduction
T
his is not a dictional)' - and nor is it an encyclopedia. It is a reference and compendium of useful information about the
converging worlds of computers, communications, telecommunications and broadcasting. You could refer to it as a guide for
the Information SuperHighway, but this would be pretentious. It aims to cover most of the more important terms and
concepts in the developing discipline of Informatics - which, in my definition, includes the major converging technologies,
and the associated social and cultural issues.
Unlike a dictional)', this handbook makes no attempt to be 'prescriptive' in its definitions. Many of the words we use
today in computing and communications only vaguely reflect their originations. And with such rapid change, older terms are
often taken, twisted, inverted, and mangled, to the point where any attempt by me to lay down laws of meaning, would be
meaningless. The information here is 'descriptive' - I am concerned with usage only.
The headwords:
T
his book therefore contains key-words and explanations which have been culled from the current literature - from
technical magazines, newspapers, the Internet, forums, etc. This is the living language as it is being used today - not a
historical artifact of 1950s computer science.
Purists can contest many of these definitions, but I'm not overly concerned with being 'correct', only with reader
comprehension - with current usage being readUy understood. And that often means navigating the inconsistencies and the
mis-uses, and understanding the implications, because sub-text is often more impo~ant than the overt usage itself.
One problem all lexicographers face, is in chOOSing which 'headwords' to include and which to ignore. My computer
database has many more than you'll find here, and if you check technical dictionaries in a bookstore there are thousands of
acronyms and terms listed. Like bacteria, they divide and duplicate evel)' second day. But the words and acronyms included
here, I believe, are the most important. They are the key to understanding the literature on convergence and its
consequences in the immediate future. And this is what Informatics is all about.
The technical level:
T
his is obviously not a reference for people just buying their first Pc. It is for those who already having a reasonable
background knowledge - they will already be readers of books and magazines on informatics technologies. And this area of
convergence is, by definition, populated by people with a high level of knowledge in one technical area, but perhaps little or
none in others. So I've tried to pitch the explanations at the level appropriate to the terms - rather than predict the
knowledge of the reader. If you need to find out what 'bandwidth' means, then obviously your information requirements are
relatively basic. If you want an explanation of 'TINA', however, you are probably already seriously involved in
telecommunications.
As a technology writer, I've also collected a whole range of useful facts over the years - data-rates, channel numbers,
frequency ranges, bandwidths, etc. This sort of information is amazingly difficult to find in much of the literature, so it has
been included here, wherever possible. This information will not be 100% correct; it is changing all the time, and it is often
varies in different countries. The information in this book has been checked and rechecked to the best of my ability, but this
is both an ephemeral and moving target. Updating and correcting information in the primal)' database is a daily event, so this
book is already out-of-date.
On-line and CD-ROM:
It
is our intention to create a CD-ROM version, and to put the full database on-line in the near future. The details have still to
be finalized. However, it is important that we get feedback from readers who find discrepancies, or who wish to suggest
additions - or who perhaps have a better and more useful explanation for some of the items. My contact details are: s. F.
Stewart A. Fist
Internet: [email protected]
CompuServe: 100033,2145 - Facsimile: [phone]
User's Guide
Author's abbreviations: Frequency:
# generic substitute for any number. Hz Hertz (cycles per second).
aka also known as. kHz kiloHertz (thousands ofHertz).
sync synchronous. MHz MegaHertz (millions ofHertz).
async- asynchronous. GHz GigaHertz (thousands of millions of Hertz).
sic as it is written. THz TeraHertz (million million Hertz)
Bit-byte numbers and rate: General:
b bit. n is often use as any integer - as in 'n x 64'.
B Byte (S-bits, unless otherwise specified). P also often means any integer - as in 'p x 64'.
ms millisecond (thousandths of a second).
kB kiloByte (thousands of Bytes).
j.LS microseconds (millionths of a second).
MB MegaByte (millions of Bytes).
mm millimeter (l/25th of an inch).
GB GigaBytes (thousand million Bytes).
cm centimeter (about 4-inches).
kb/s kilobit/sec. (thousands of bits per second). m meter (roughly 40-inches).
Mb/s Megabit/sec (millions of bits per second). km kilometer (5/8ths of a mile).
Gb/s Gigabit/sec (thousand million bits per second). in inch (25 mms)
Indexing
The terms are generally retained in the normal word order word in one place, check the other. 'Halftone' could also be
rather than strict alphabetic order of the letters - but there are written as 'Half tone' (but it generally isn't) and be further down
some exceptions and some traps. in the listing so check both.
For instance, the sequence of head-words will be:
Acronyms/abbreviations:
page
In this industry, the acronym is widely used, while the full-out
page description languages
term is rarely heard. I have tended to list under the term most
page printer used - and this tends to be the acronym (but not always).
paged virtual memory You'll find ATM under the acronym, not under 'Asynchronous',
pagination however the industry uses 'BiSync' rather than BSe.
paging
The obvious:
You will find that this is different in some dictionaries because
I've tried also to avoid filling up the book with the bleeding
they give the alphabetic order, more weight than the word
obvious. You wont find Network Adminstrator, for instance,
divisions.
because I assume you are all intelligent enough to realise that
However the word-approach sometimes breaks down with
this person administers a network. You will, however find
acronyms and abbreviations. For instance, 'BISDN' (also written
Network Administration, since it spells out the common
'E-ISDN,) could be in the front of the B section (as a distinct
functions which come under this heading.
word), along with' E-channel', and 'E-spline', but it is back in
the main body, with 'BiSync' and 'bistable'.There is no right and Cross references:
wrong way to handle these. Cross references are not just to closely related items; think of
Numbers are sorted ahead of alpha characters. So the head these as hypertext links. I've tried to give you cross-references
word 'BSZS' will precede 'back-porch'. Pure numbers, such a to other useful or interesting items. These might be an alternate
'486' and '5/6 tone' are in their own Numbers section, technology, or other technologies that share a similar
preceding the A-listings. They are in true number order - not characteristic, or where there is a concept which (to me
on a character-by-character basis. anyway) has a relationship of some kind. With these references
Word splits are a particular problem, so look out for non you should be able to track your way through the listings even if
standard splits or for words that may be joined. If you don't find you don't quite know what you are looking for.
3-axis stabilized
# 1GL
First generation languages. Machine code which is not really a
language at all but rather a way of accessing memory locations
using mnemonic codes. See language generations
1MB barrier
See 640kB barrier.
OTIP 2:7 interleave
Zero Transmission Level Point. The reference point in a trans See RLL.
mission system, from which relative losses are measured.
2B1Q
1/4 (one-quarter) Two binary, one quaternary. A very simple baseband line-cod
• Audio tape standards: See Quarter-inch. ing system used in the VSA for ISDN. It is a multi-level line
code which uses two positive, and two negative voltages - so
• Computer tape standard: See QIC.
the receiver must detect both amplitude and polarity of the sig
1/2 (half) nals, but not the phase.
• Code: A one-half code is one where one in every two bits It tends to be susceptible to impulse noise. For this reason
carries information and the other is redundant and used for QAM techniques are generally more suited to higher data-rates
error correction. It is a term used mainly in the paging industry (see CAP), although 2B1Q works extremely well in the local
and for deep-space transmissions where you can't ask data to loop at 160kb/s.
be re-sent. FLEX and POCSAG are 2/3 codes, while GSC is a 1/2 In America, both ISDN and HDSL use similar line-coding
code - so GSC is relatively inefficient - but it may also be because 2BIQ cuts the overall bit stream line-rate in half, since
more robust and able to correct errors when the owner is in a 2-bits are carried in each symbol. This also has advantages
lift-well in a steel-and-concrete building. when bundling HDSL pairs and other cr-l) pairs, in that the
power spectrum is centered much lower, which minimizes
• Tape systems. See half-inch tape.
crosstalk.
2/3 (two-thirds) • See quatemary, ISDN and TCM.
Code: A two-thirds code is one where two out of every three
2GL
bits carries information, and one in three is redundant. It is a
Second generation languages. Assembly languages which use
term used mainly in the paging industty. FLEX and POCSAG are
cryptic mnemonic commands. See assembly language and lan
2/3 codes, while GSC is a 1/2 code - so GSC is relatively ineffi
guage generations.
cient.
2-wire
3/4 (three-quarter)
• Telephony: This means the typical local loop twisted-pair
Tape standard: See V-matic.
connection. It applies even to the 'quad' wire that probably
1: 1 interleave carries the signals into your home. See wires.
When a magnetiC disk has an interleave factor of only one, it
• Video: This means component systems of the Y/C type
means that the head can read every sector on one track in a
which requires two different connections between machines in
single disk rotation. The disk controller must be able to proc
any post-production facility (one for the luminance, and one
ess the data at a fast enough rate so that consecutive sectors
for the color). Of course they also need another for audio, but
can be handled without needing a pause. This is either a very
this isn't counted. 'Wire' here means a full cable. See 3-wire.
fast controller, or a slow disk. See RLL.
3+ NOS
IB1Q
An etwork operating system from 3Com.
See HDSL and 2B 1Q .
3-axis stabilized
1Base-S
These are geostationary communications satellites which have
This is the IMb/s version of 802.3 Ethernet over unshielded
large flat 'wing' panels of solar cells (as distinct from the 'barrel
twisted pair(UTP). It was originally promoted as StarLAN by shaped' spin-stabilized type). The large wings on these satel
AT&T. It is a CSMNCD system using twisted pair telephone
lites can generate more power than the cylindrical type so they
cables. The advantages of this approach are that a company's
are Widely used for direct broadcasting where output power is
LANs wiring will be installed along with its telephone wiring in
essential. Gyroscopic stabilizers are proVided to handle small
the same cables, all radiating from a central hub.
angle corrections (up to 5°), and larger changes are made by
• lOBase-T should be considered as a highs peed version of judicial use of the thrusters. See nadir face.
this technology.
3·D 2
3·D 3·D sound
Despite common perceptions, the third dimension in video is This differs from surround sound (with four or five speakers),
not just achieved by presenting slightly different views of a but it achieves much the same results from two speakers ... so
scene to the two eyes. This is called stereopsis, and it is only they say! 3D sound is a feature on many of the new PC sound
one of the mechanisms used by the brain to judge 'depth' in a cards. See Dolby, Prologic and wave-table.
scene, and then normally only for objects within a few meters.
300
Other image-factors which help the 3rd Dimension illusion
Av ideo games console and standard which will probably have
of 'depth' are generally present in all movies. They are:
applications in new interactive set-top boxes in the future cable
- Relative size. Objects closer to the camera appear larger television systems. It incorporates MPEG2 compression and
than objects at a distance. They also move more slowly CD-Audio and CD-ROM standard. Scientific Atlanta is now
across the screen. using it in its new digital set-top boxes.
- Relative height. Unless your eye or camera is at ground 3DO has been developed by a partnership of Electronic Arts
level, objects higher in the image plane (but only to the (the world's largest producer of video games), Matsushita (the
limit of the hOrizon line) will be further away than objects world's largest manufacturer of consumer electronics), Time
lower in the image. Warner (the world's largest cable distribution company), and
- Cut-off. Near objects tend to block off (obscure from view) AT&T (the world's largest telephone company). It was also
parts of more distant objects. boosted as the world's greatest breakthrough in games and
superhighway standards, but it seems over the last few years to
- Shade and shadows. Shading of light on a spherical
have become the world's greatest non-event.
object, for instance, gives unambiguous information about
its shape. Textures can be seen on close surfaces, but not Their new M2 64-bit game unit has a graphics performance
on distant. of one million polygons per second (peak) and a sustained rate
of 700 kilopolygons per second. It runs a PowerPC 602 64-bit
- Aerial haze. Distant mountains take on a bluish coloration.
processor at 66MHz, and has a dedicated graphiCS IC, and
- Parallax: If the camera moves even slightly sideways, the
special VO control ICs. Af loating point processor handles anti
relative movement and obscuration of close vs. distant
aliasing, shading and other image processing. It also provides
objects gives the viewer excellent judgement of depth.
an MPEG-1 decoder and a 24-bit DSP for audio. 4MBytes of
- Stereopsis: This is only present in the special 3D movies DRAM are provided as main memory.
using red-blue or polaroid glasses to separate the two
images. A slightly different view is then received by each 3GL
eye, because the two images were recorded by cameras Third Generation Language. These are high-level languages
which were horizontally separated by a few inches. such as Basic, Fortran, Cobol, and C, etc. which are written
3D graphics were only really possible on powerful workstations using English-like commands, and can be made transportable
between various platforms. They need to be interpreted or
until recently. Now these techniques are moving onto pcs.
compiled to run. See language generations
There are a number of different approaches in the labs, but
currently the de facto standard must be OpenGL 3D libraries 3·wire
and APls, which are supported by Microsoft and IBM. This is A video production term used with YUV and YIQ component
now standard in Windows NT and is an option in Windows 95. editing and post-production equipment. The three-wire (actu
Warp has support also. ally three separate connections) is necessary to carry the differ
• Sharp has demonstrated a 'twin-LCD' form of 3D TV screen ent video components (luminance and two color-difference
which has two superimposed flat-screens in a sandwich. The signals) which remain as separate Signals through the post-pro
viewer sees one screen layer with the right eye, and the other duction process. This is the best way to keep the video at the
with the left. You don't need special polaroid or coloured highest quality, but most post-production facilities can only
glasses, but your eyes must be at a standard distance from the handle composite video.
screen. 4:1:1
• The Nintendo system uses two displays, each consisting of Av ersion of the 4:2:2 component video standard which is used
a one-dimensional Red LED array and a synchronized scanning in news gathering where color quality is not considered so
mirror. This is the Private Eye technology of RTI. The image important. Two thirds of the bits are devoted to the definition
looks to be about 30 cm away and directly in front of the of the luminance image, and only one third divided between
viewer: it has four levels of tone in red against a black two color-difference signals .. See color difference and 601 CCIR.
background.
4:2:0
• There's a new Sanyo 3D system that doesn't require glasses. A variation on the 4:2:2 component video standard where a
It is correctly called 3-D LCD. composite color signal is only included with every second line.
3 8mmtape
Another source says that the Red (R-Y) signal will be transmit 4-phase modulation
ted in one field, and the Blue (B-Y) in the next field (similar to Any modulation technique which yields dibits for each baud.
SECAM in analog). The MPEG2 main leveVmain profile encod So each transmitted 'event' or 'symbol' can produce dibits of
ers use this coding technique to reduce the bit rate to 8Mb/s. 00, 01, 10, or 11. This doesn't necessarily refer to 'phase' as in
See color difference and 601 CCIR. sine-wave cycle, it can sometimes mean just 'four-level'.
4:2:2 4-wire
Four parts of luminance, and two parts each of the two color See four-wire and wire.
difference signals. This is the ITU-R Recommendation 601 for 5
digital component video production and distribution (but not
The number five, on its own, is sometimes being used to indi
transmission) without compression. cate a Pentium processor. You may see it during discussions
The standard is now widely used around the world and both about new computers, in the form: ". .. the Acme 5/100 ... "
50Hz and 60Hz versions exist. Both have a luminance sampling which means the Acme PC has a Pentium running at 100MHz.
frequency of 13.5MHz using 8-bit linear PCM (the '4' signal),
5/6 tone
and two chrominance difference signals (R-Yand B-Y) sampled
An early tone paging code developed by Motorola, which relies
at halfthat rate (6.75MHz).
on unique addresses using any five of ten possible frequencies.
The D-1 videotape recorder standard was based on this
The sixth tone, was a way of later extending the address to pro
recommendation but with lO-bits per sample (8-bits is now
vide priority messages, coded instructions etc.
thought to be insufficient for primary sampling), producing a
This standard has now been superseded by POCSAG and
serial bit-rate of270Mb/s. The samples are then rounded down
GSC coding systems with tone, numeric and later alpha
to 8-bits for in-house transmission.
standards included. See CAP, RDS, TAP, ETC, PET, DCO and
• The ETSI/EBU-300.l74 television transmission standard is FIEX.
designed to allow compression of these signals to 34Mb/s with
5GL
virtually no loss of quality. From 1996 on, however, the most
Fifth generation language. See.
common output will be as MPEG2 compressed video. See 601
CCIR and widescreen. 5-level code
The Baudot code or ASCII Alphabet No.2 (See)
4/6GHz satellites
See C-band. 7E1
The old asynchronous modem standard for communicating
4-ary
with mainframes. This is 7-bits, even parity, and 1 stop-bit (plus
See quaternary.
1 start-bit which is assumed).
4B31 8-to-14 coding
4-Binary with 3-Ternary code. This is a form of AMI where See EFM and channel coding.
binary is mapped into a ternary transmission system (zero, plus
8-bitCPU
both + and - voltages). Ag roup of four binalY bits is mapped
See 32-bit CPU.
into true three-state ternary code using look-up tables -
achieving a baud-rate reduction of 25%. This line-code tech 8-bit toggle
nique is used for Basic Rate ISDN in European countries. This is a command for some modems which allows them to
switch the 8th bit in each byte off (set it to 0). This is some
4B5B
times necessary to prevent gibberish on the screen, resulting
This is a code translation technique used in FDDI and other
from the transmission of a 7-bit ASCII byte, but with the 8th bit
transmission systems where the code is converted from 4-bit
set to 1 for some internal communications reason. This causes
nibbles to 5-bit symbols before NRZI line-coding. The idea is to
the PC to reproduce the extended ASCII character rather than
maintain clock synchronization by ensuring that there can
the normal alphanumeric character.
never be a long string of zeros or ones on the line.
88/108
In FDDI, the use of 4B5B means that to achieve an actual
IBM's line-coding system used in Fiber Channel and some ATM
'throughput' rate of 100Mb/s, the network must operate at
implementations. Eight data bits are translated to a lO-bit
125Mbp/s. This is also used more recently in IsoEthernet.
group, with the two extra bits being 'disparate control' (error
4GL detection and timing recovery).
See fourth generation languages.
8mmtape
4mm tape A very popular tape back-up standard for computers derived
See DataDAT and DAT. from Super-8 video, which uses video helical scan recording